Approaching the most critical juncture of his 30-year political career, Rep. Gary Condit goes on the offensive today -- sending out letters to constituents while preparing for his first prime-time interview in the wake of Chandra Levy's disappearance.

Condit's mass mailing to constituents will assure them he was not involved in the disappearance of the 24-year-old former Washington intern, sources said.

It will be mailed today and begin reaching 217,000 households throughout Condit's 18th Congressional District tomorrow, sources said.

The Democrat from Ceres will then sit down for a half-hour interview with Connie Chung on ABC's "Primetime Thursday," to be broadcast locally on Channel 7 at 10 p.m.

CNN reported last night that Condit also planned an interview tomorrow with a local television station to air after the national network event, in addition to a talk with a local newspaper and two weekly newsmagazines.

"You're not going to send a letter, and give an interview, and all of a sudden be healed," said Richie Ross, Condit's Sacramento-based political consultant, told The Chronicle yesterday. "You have to take this thing in steps."

Levy, a Modesto resident who was in Washington for an internship, was last seen April 30. Condit, who reportedly has told authorities they were having an affair, has not spoken publicly about their relationship.

The ABC interview and his mailing to constituents come as criticism of the congressman has increased. Condit has remained in virtual seclusion since he returned home to the Central Valley after Congress recessed more than two weeks ago.

With 14 months until a potential re-election, Condit's political strategy is shaping up as supporters plan a rally tomorrow in Merced and invitations are sent to his Oct. 20 "Condit Country" fund-raiser.

But Levy's parents also stepped up their pressure last night, making clear they would not be satisfied with Condit's high-profile public outreach.

Susan and Robert Levy "don't want to hear anything about the relationship . . . how he felt about Chandra," their attorney, Billy Martin, said on CNN. "They think (Condit) has information that can help them, and they think it's been reckless not to come forward sooner."

But Condit's camp said he believes it's time to break almost four months of public silence since Levy's disappearance.

"We would be satisfied if we took a step in getting people to stop thinking he had something to do with the disappearance," Ross said. "Let's get that job done. That may take a month. Let's get the most basic, simple, obvious thing done."

Condit will then tackle "rebuilding a relationship with the voters here," Ross said.

Condit intends -- in his letter and on the air -- to stress he has been deeply concerned about the missing woman as he has shown by cooperating with police the FBI to help find her, Ross said.

Already, Condit's interview with Chung has been focus of intense media scrutiny. And pundits are buzzing about the format -- a 30-minute "live to tape" interview, shown unedited.

Ross said yesterday that Condit required no ground rules from Chung or ABC - - and the network decided on the format that best suited them.